Search Publications
Enhancement of the helium resonance lines in the solar atmosphere by suprathermal electron excitation - I. Non-thermal transport of helium ions
Jordan, C.; Smith, G. R.
Models of the solar transition region made from lines other than those of helium cannot account for the strength of the helium lines. However, the collisional excitation rates of the helium resonance lines are unusually sensitive to the energy of the exciting electrons. Non-thermal motions in the transition region could drive slowly ionizing heliu…
Near- and mid-infrared colours of star-forming galaxies in European Large Area ISO Survey fields
Serjeant, S.; Morel, T.; Gruppioni, C. +6 more
We present J- and K-band near-infrared (near-IR) photometry of a sample of mid-infrared (mid-IR) sources detected by the Infrared Space Observatory (ISO) as part of the European Large Area ISO Survey (ELAIS) and study their classification and star-forming properties. We have used the Preliminary ELAIS Catalogue for the 6.7-µm (LW2) and 15-&m…
XMM-Newton observations of the asynchronous polar BY Cam
Cropper, Mark; Ramsay, Gavin
We report observations of the asynchronous polar BY Cam made using XMM-Newton. We find evidence for two accretion regions which have significantly different spectra. In both regions we find evidence for hard X-ray emission from the post-shock flow while we observe a distinct soft X-ray blackbody component in only one. We detect two emission lines …
On the pulsation parallax of the variable star RR Lyr
Marconi, M.; Bono, G.; Caputo, F. +2 more
We show that a straightforward application of the predicted relation connecting the absolute K magnitude of fundamental RR Lyrae variables to their period and metal content, together with current evolutionary predictions on the mass and luminosity of Horizontal Branch stars, supply a distance estimate to the prototype star RR Lyr in close agreemen…
An irradiated accretion disc in the narrow-line Seyfert 1 RE J1034+396?
Soria, R.; Puchnarewicz, E. M.
We model the optical to X-ray continuum spectrum of the narrow-line Seyfert 1 galaxy RE J1034+396. We show that the flat optical spectrum is consistent with emission from an irradiated accretion disc. The X-ray emission can be modelled with a disc blackbody and a Comptonized component. The temperature at the inner edge of the disc Tin=(…
The host galaxies of Type Ia supernovae at z= 0.6
Farrah, D.; Rowan-Robinson, M.; Mattila, S. +2 more
We examine the host galaxies of high-redshift Type Ia supernovae (SNe Ia) using archival I- and R-band data from the Hubble Space Telescope. The SNe Ia host galaxies show a wide variety of morphologies, including undisturbed ellipticals, spirals and disturbed systems. SNe Ia are also found over a wide range of projected distances from the host gal…
The massive double-lined O-type binary HD 165052
Barbá, R. H.; Morrell, N. I.; Arias, J. I. +3 more
We present a new optical spectroscopic study of the O-type binary HD 165052 based on high- and intermediate-resolution CCD observations. We re-investigated the spectral classification of the binary components, obtaining spectral types of O6.5V and O7.5V for the primary and secondary, respectively, finding that both stars display weak CIIIλ5696 emi…
On the source of the flaring activity in AB Doradus: the UV spectral signatures
Gómez de Castro, Ana I.
AB Dor is a young, 30-Myr-old, low-mass star with a short rotation period and strong flaring activity. In this work, a detailed analysis of the flaring activity is carried out based on ultraviolet spectral tracers of hot (T ~105 ) plasma, namely HST /GHRS profiles of the Civ[uv1] and Siiv[uv1] lines. The quiescent component has been sub…
Mrk 1014: an AGN-dominated ultraluminous infrared galaxy
Lutz, D.; Sturm, E.; Boller, Th. +1 more
In this paper we report on an XMM-Newton observation of the ultraluminous infrared QSO Mrk 1014. The X-ray observation reveals a power-law-dominated (Γ~ 2.2) spectrum with a slight excess in the soft energy range. Active galactic nucleus (AGN) and starburst emission models fit the soft excess emission equally well, however, the most plausible expl…
The origin of the strings in the outer regions of η Carinae
Redman, M. P.; Meaburn, J.; Holloway, A. J.
The narrow optical filaments (`strings' or `spikes') emerging from the Homunculus of η Carinae are modelled as resulting from the passage of ballistic `bullets' of material through the dense circumstellar environment. In this explanation, the string is the decelerating flow of ablated gas from the bullet. An archive Hubble Space Telescope image an…